Adhesive for plaster of paris for bandage use



Patented Oct. 13, 1953 ADHESIVE .FOR PLASTER .OF PARIS FOR .BANDAGE USE James Joseph Eberl, fihester, and Alvin Richard Ingram, Glens'haw, ;Pa., assignors :to Johnson -& Johnson, a corporation of New Jersey "No Drawing. Application February 1, 1950,, Serial .-No. 141,848

.11 =G1aims. 1

'This invention relates to a bandage for use in surgery, orthopedy and'derma-tology, and particularly one-of the type wherein a flexible-fibrous carrier i impregnated with a composition containing plaster of Paris together with an adhesive binder to prevent plaster loss.

Such a bandage is made usually in the form of a roll which, -in-use, is immersed in-water to hydrate the plaster and, while still wet, wrapped around the member to be immobilized. During the wrapping process the bandage is molded to the shape of the member and rendered substantially homogeneous throughout by rubbing or handling. The bandage sets .to form a hard and rigid structure.

Plaster of Paris bandages, as heretofore made, have .not been entirely satisfactory. They sometimes lose as much as twenty-five'per cent of the plaster during the immersion process and during application to the member to be immobilized. They require great care :in .handling to guard against telescoping, i. e., the tendency for the inner convolutions of the bandage to slip from within the outer convolutions as the bandage becomes thoroughly wetted. Where telescoping occurs, it is impossible to use a bandage in the manner intended.

In the improved bandage, telescoping, for all practical purposes, has been eliminated. It isnnnecessary to use special precautionary techniques to guard against inter-layer slippage :cluring immersion to saturate the bandage prior to use. During immersion, little o-r'no plaster is lostand this is likewise true when the -fbandage Iis squeezed to expel excess water. The tests haves'hownzthat during the immersion and squeezing process the plaster lost from the improved bandage is inthe neighborhood :of 0.1%. It is true that as the bandage is molded on themeniber .to be immobilized some plaster comes on on the .nper:a. tors hands but this amounts to nom-ore than about 3 to 5% of the total plaster in the bandage. i'llhus, about '94 to 96% of "the original :plaster 'in the bandage is delivered to the :cast. The result that more plaster per bandage is carried to the cast and fewer bandages-are required for strong,

dependable immobilization. To state the matter diiferently, bandages which initially :contain a given amount of plaster iproducea hutch stronger cast than :earlier types of bandages containing initially :a corresponding amount :of plaster because .the excessive plaster loss .sufiered by the latter during application.

According to the present invention, the plaster oi Paris (calcium sulfate hemi-hydrate) is held in :place .on the flexible carrier prior to use by :an adhesive which is insoluble in water or .at least insoluble to such an extent as not :to swell (or otherwise be alfected materially in the period-re quired to wet out the plaster. Theadhesive 'is not present in the :fotm of a film .as in .the caseof the soluble adhesives that have heretofore been :used, but rather is dispersed intermittently in :the form of tiny discrete particles over the surfaceof the plaster particles binding them one :to another and to the flexible carrier.

It has been discovered that thesefiect of threadhesive, in reducing plaster ilossduring :the immersion process and eliminating telescoping during application to the member to be immobilized due to :poor lamination, is :governed by the quantity of adhesive used. Plaster of Paris bandages containing an adhesive, :based .on dry weight, in anamount within thez-rangelof 2f'rom10.l% to 2.51%., based onthe d-ry weightsof plaster-of Paris, exhibit excellent laminating properties andwheniused in the immobilization of body .members, deliver to the cast approximately 94 to 96% of the original plaster in the bandage.

'In the absence of a film-or matrix in which the plaster of Paris particles otherwise would be embedded, there is -nothing to;delay or inhibithydration when the bandage .immersedsince durin immersion the water will have immediate access to the .hemi-hyd-rate particles. Furthermore, throughout the immersion ,process, the insoluble, or relatively insoluble {discrete particles of .adhesive will continue to perform their binding function. They enable excess water .to be r squeezed out without plaster lossso that the bandage will setanddry inthe-shortest possible ,period. Less adhesive is required than is .thccase if anontinuous watersoluble film is used.

In order to distinguish as a class the adhesive materials it is proposed to use, they have been termed, in the absence :of a better ,name, nonswellable adhesives and they may be either insoluble in Water or so slowlysolublein water as not-to swell during the period of wetting out and application :of the bandage as previously described. Among the materials in this category which may be used in practising the invention there are included the water insoluble polymers andcopol-ymers of vinyl acetate and-methacrylate or acrylate esters; water insolubleeellulosicothers and esters; natural and synthetic rubbers; coumaroneindene resins; rosinsand thoseiderivatives of rosin which are water insoluble. These materials are given by way of example only since. indeed, any adhesive which is water insoluble to the extent previously mentioned may be used so long as it may exist in the form of an emulsion or dispersion which is stable under the conditions that exist during impregnation of the flexible carrier with the plaster of Paris.

Several methods may be used to incorporate the non-swellable adhesive in the plaster of Paris in the form of tiny discrete particles. One method is analogous to the acetic acid process described in the Mathey Patent 1,726,403, except that the non-swellable adhesive is a high viscosity water insoluble polyvinyl acetate which is introduced in the form of an emulsion. A suitable polyvinyl acetate emulsion ior the purpose is obtainable in this country from E. I. du Pont de Nemours under the name Elvacet 81A-900. This emulsion contains 55% by weight of polyvinyl acetate in water. For best results its viscosity in acetic acid (1 part emulsion to 9 parts glacial acetic acid by weight) should range between 300 to 2800 centipoises. This entire range is satisfactory but most eficient results are obtainable within the range 700 to 2000 centipoises. Below this range the adhesive suffers somewhat in adequacy, whereas above the range the polyvinyl acetate is not as effectively softened by the acetic acid, with the result that some of its adhesive action is lost. However, any disadvantages that might result from using the lower or the higher range may be compensated for by increasing the amount of emulsion per unit weight of plaster of Paris.

Particle fineness in the emulsion will be satisfactory if there is no significant settling out of the larger particles within minutes after agitation of a mixture of 1 pint of the emulsion to 25 pints of water.

To prepare a suitable bandage, a batch of material using the polyvinyl acetate emulsion described above may be made up according to the following example:

Example I Plaster of Paris lbs 200 Water lbs 56 Acetate acid (45%) lbs 46 Polyvinyl acetate emulsion ml 600 to 1800 The polyvinyl acetate emulsion is added to the water and the mixture agitated until complete dispersion is obtained. The dispersed emulsion is added slowly to the acetic acid while the latter is stirred. After two minutes stirring, the plaster of Paris is added in powdered state and the stirring continued until a smooth creamy slurry results. The slurry is spread on gauze, crinoline or other flexible carrier and then dried in any approved manner.

The amount of water and acetic acid used may be varied from that given in the above example to vary the consistency of the slurry and to regulate the setting time of the plaster in the completed bandage. The stirring time after the addition of the plaster of Paris likewise affects the setting time. Such matters, however, are within the province of the operators skilled in the art. For example, the above batch with 900 ml. of Elvacet 81A-900, stirred for fifteen minutes after adding the plaster of Paris, gave a bandage having a setting time of five to eight minutes. This bandage lost a negligible amount of plaster (less than 1%) when immersed in water, delivered from 94 to 96% of the plaster to the cast, and would not telescope until it had been soaked in water from 1% to 2 minutes. Within 3 to 5 seconds, however, the bandage will have soaked up enough water for use. Thus, for all practical purposes, telescoping has been eliminated. Some idea may be had of the actual amount of adhesive used in this bandage when it is realized that 900 ml. of Elvacet 81A-900 weighs 2.15 lbs., the polyvinyl acetate solids content being about 1.18 lbs.

Another process which may be used to incorporate a non-swella-ble adhesive in a plaster of Paris bandage involves the use of ammonium borate to retard the setting of the plaster of Paris during the coating process. Ammonium borate, even in very small quantities, acts to retard the setting of plaster of Paris and it is particularly desirable for the purposes of this invention since, when it decomposes as the bandage is dried after coating; boric acid is left which has a negligible effect on the setting time of the plaster when the bandage subsequently is placed in use.

There follow several examples of batches or mixtures involving the foregoing process and which may be used to produce bandages according to the instant invention.

Example II Pounds Plaster of Paris 100 Water to 100 Copolymer of vinyl acetate and acrylic ester emulsion 2 to 4 Boric acid .5 to 2 Aqua ammonia (29%) .685 to 2.8

Example III Plaster of Paris 100 Water 50 to 100 Polyvinyl acetate emulsion 2.5 to 6 Boric acid .5 to 2 Aqua ammonia (29%) .685 to 2.8

Example IV Plaster of Paris 100 Water 50 to 100 j Copolymer of vinyl acetate and methyl acrylate emulsion 2.5 to 6 Boric acid .5 to 2 Aqua ammonia (29%) .685 to 2.8

The emulsion referred to in Example 11 is one made in this country by E. I. du Pont de Nemours and sold under the designation TLF-223E. It contains 32% solids.

The polyvinyl acetate emulsion referred to in a smooth slurry which is applied to a carrier ofthe usual type such as crinolinagauze or-other flexible fibrous material.

The coated carrier is dried, preferably by heat insufficient to bring the temperature of the coated carrier above F., which is not suflicient to cause the adhesive to melt down to a' continuous film, but which is so regulated that the hydrolysis of the ammonium borate (formed from the boric acid and aqua ammonia) is as complete as possible. 1 T

In general, the emulsions of water insoluble polymers to which reference has been made heretofore are prepared by dispersing in water the monomer of the material together with the dispersing agent and then polymerizing. Usually, the dispersing agent is a colloidal polyhydric agglutinant. Thus, in the polyvinyl acetate emulsion Elvacet BIA-900, the colloidal polyhydric agglutinant is polyvinyl alcohol, which is present to the extent of about 3% by weight. This emulsion, for stability, is builered to a pI-I of between 4 and 7 by a suitable agent such as sodium acetate.

The invention has been described with reference to its preferred embodiments but other methods and materials within the inventions spirit will occur to those skilled in the art. For example, the hot water process in which no retardant is used but in which the water slurry is maintained around. 95 C. may be used provided the non-swellable adhesive is in the form of an emulsion which is stable at such temperatures. It should be noted that substantially any nonswellable adhesive may be used provided it is in the form of an emulsion which is stable at the conditions under which the plaster of Paris slurry is made. The invention, therefore, is to be limited only by the prior art and the scope of the appended claims.

This application is a continuation-in-part of copending U. S. patent application, Serial No. 654,819, filed March 15, 1946, now abandoned.

What we claim is:

l. A plaster of Paris bandage comprising a flexible carrier and a coating of plaster of Paris thereon, the plaster of Paris being in the form of fine particles bonded to one another and to the flexible carrier by discrete particles of an adhesive which is non-swellable in water of the group consisting of high viscosity polyvinyl acetate, copolymers of vinyl acetate-acrylic ester, and copolymers of vinyl acetate-vinyl chloride, said adhesive being dispersed throughout the plaster of Paris coating, the adhesive being present in an amount within the range of from 0.1 to 2.5% based on the dry weight of plaster of Paris.

2. The method of preparing a plaster of Paris bandage which comprises making a water slurry of plaster of Paris in the presence of a sufiicient amount of retardant of the group consisting of acetic acid and ammonium borate to prevent setting of the plaster, introducing an emulsion of a water insoluble vinyl acetate polymer into the slurry, coating a flexible carrier with the slurry and drying the carrier whereby there is left on the carrier plaster of Paris in the form of fine particles bonded to one another and to the flexible carrier by the insoluble vinyl acetate polymer in the form of discrete particles dispersed throughout the coating, adhesive being present in an amount within the range from 0.1 to 2.5% based on the dry weight of plaster of Paris.

3. A bandage according to claim 1 in which the adhesive is high viscosity polyvinyl acetate.

4. A bandage according to claim 1 in which the adhesive is a copolymer of vinyl acetate and acrylic ester.

5. A bandage according to claim 1 in which the adhesive is a copolymer of vinyl acetate and vinyl chloride.

6. A plaster of Paris bandage comprising a flexible carrier and a coating of plaster of Paris thereon, the plaster of Paris being in the form of fine particles bonded to one another and to the flexible carrier by an adhesive which is dispersed throughout the plaster of Paris before coating said plaster of Paris on said carrier, by mixing an emulsion of said adhesive with a water slurry of said plaster of Paris in the presence of a sufficient amount of a retardant 0f the group consisting of acetic acid and ammonium borate to prevent setting of the plaster, said adhesive being nonswellable in water and present in an amount within the range of from 0.1 to 2.5% based on the dry weight of plaster of Paris.

7. A bandage according to claim 6 in which the adhesive is a high viscosity vinyl acetate polymer.

8. The method of preparing a plaster of Paris bandage which comprises making a water slurry of plaster of Paris in the presence of a sufficient amount of a retardant of the group consisting of acetic acid and ammonium borate to prevent setting of the plaster, introducing an emulsion of a water insoluble polyvinyl resin into the slurry, coating a flexible carrier with the slurry and drying the carrier whereby there is left on the carrier plaster of Paris in the form of fine particles bonded to one another and to the flexible carrier by the insoluble polyvinyl resin dispersed throughout the coating, said adhesive being present in amount within the range from 0.1 to 2.5% based on the dry weight of plaster of Paris.

9. A plaster of Paris bandage material comprising a flexible carrier and a coating of plaster of Paris thereon, the plaster of Paris being in the form of fine particles bonded to one another and to the flexible carrier by a nonwater-swellable adhesive which is dispersed throughout the plaster of Paris before coating said plaster of Paris on said carrier, by mixing an emulsion of said adhesive with said plaster of Paris to form a water slurry of plaster of Paris containing adhesive, said adhesive at the time the plaster of Paris is coated on said carrier being nonswellable in water and present in an amount within the range of from 0.1 to 2.5% based on the dry weight of plaster of Paris.

10. A bandage material according to claim 9 in which the adhesive is a water insoluble polyvinyl resin.

11. A bandage material according to claim 9 in which the adhesive is a water insoluble vinyl acetate polymer.

JAMES JOSEPH EBERL. ALVIN RICHARD INGRAM.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,152,670 Shutte Apr. 4, 1939 2,218,710 Herrmann Oct. 22, 1940 2,483,806 Buckley et a1 Oct. 4, 1949 FOREIGN PATENTS Number Country Date 368,421 Italy Feb. 15, 1939 388,031 Great Britain Feb. 14, 1933 OTHER REFERENCES Canadian Medical Association Journal for August 1945, pp. -1. Copy in Div. 55. 

9. A PLASTER OF PARIS BANDAGE MATERIAL COMPRISING A FLEXIBLE CARRIER AND A COATING OF PLASTER OF PARIS THEREON, THE PLASTER OF PARIS BEING IN THE FORM OF FINE PARTICLES BONDED TO ONE ANOTHER AND TO THE FLEXIBLE CARRIER BY A NONWATER-SWELLABLE ADHESIVE WHICH IS DISPERSED THROUGHOUT THE PLASTER OF PARIS BEFORE COATING SAID PLASTER OF PARIS ON SAID CARRIER, BY MIXING AN EMULSION OF SAID ADHESIVE WITH SAID PLASTER OF PARIS TO FORM A WATER SLURRY OF PLASTER OF PARIS CONTAINING ADHESIVE, SAID ADHESIVE AT THE TIME THE PLASTER OF PARIS IS COATED ON SAID CARRIER BEING NONSWELLABLE IN WATER AND PRESENT IN AN AMOUNT WITHIN THE RANGE OF FROM 0.1 TO 2.5% BASED ON THE DRY WEIGHT OF PLASTER OF PARIS. 